diff --git a/csdr/csdr.py b/csdr/csdr.py
index 9d23978..260da7a 100644
--- a/csdr/csdr.py
+++ b/csdr/csdr.py
@@ -241,7 +241,7 @@ class dsp(object):
             if self.fft_compression == "adpcm":
                 chain += ["csdr compress_fft_adpcm_f_u8 {fft_size}"]
             return chain
-        chain += ["csdr shift_addition_cc --fifo {shift_pipe}"]
+        chain += ["csdr shift_addfast_cc --fifo {shift_pipe}"]
         if self.decimation > 1:
             chain += ["csdr fir_decimate_cc {decimation} {ddc_transition_bw} HAMMING"]
         chain += ["csdr bandpass_fir_fft_cc --fifo {bpf_pipe} {bpf_transition_bw} HAMMING"]
@@ -331,7 +331,7 @@ class dsp(object):
             return chain
         elif which == "bpsk31" or which == "bpsk63":
             return chain + [
-                "csdr shift_addition_cc --fifo {secondary_shift_pipe}",
+                "csdr shift_addfast_cc --fifo {secondary_shift_pipe}",
                 "csdr bandpass_fir_fft_cc -{secondary_bpf_cutoff} {secondary_bpf_cutoff} {secondary_bpf_cutoff}",
                 "csdr simple_agc_cc 0.001 0.5",
                 "csdr timing_recovery_cc GARDNER {secondary_samples_per_bits} 0.5 2 --add_q",
diff --git a/owrx/source/resampler.py b/owrx/source/resampler.py
index 6afe50c..1f6a4e1 100644
--- a/owrx/source/resampler.py
+++ b/owrx/source/resampler.py
@@ -1,10 +1,4 @@
 from .direct import DirectSource
-from . import SdrSource
-import subprocess
-import threading
-import os
-import socket
-import time
 
 import logging
 
@@ -29,7 +23,7 @@ class Resampler(DirectSource):
     def getCommand(self):
         return [
             "nc -v 127.0.0.1 {nc_port}".format(nc_port=self.sdr.getPort()),
-            "csdr shift_addition_cc {shift}".format(shift=self.shift),
+            "csdr shift_addfast_cc {shift}".format(shift=self.shift),
             "csdr fir_decimate_cc {decimation} {ddc_transition_bw} HAMMING".format(
                 decimation=self.decimation, ddc_transition_bw=self.transition_bw
             ),